JP2000-272405A, published by the Japan Patent Office in 2000, proposes a hydraulic drive circuit for a concrete agitating drum mounted on a ready-mixed concrete agitating truck. The agitating drum is driven by a hydraulic motor.
In this hydraulic drive circuit, the hydraulic motor is supplied with pressurized oil from a variable capacity hydraulic pump via a connection switch-over valve. By operating the connection switch-over valve, the flow direction of the pressurized oil supplied from the variable capacity hydraulic pump to the hydraulic motor is reversed, thereby enabling the hydraulic motor to drive the agitating drum in a normal direction and in a reverse direction.